These images show a stretch of the Mississippi River just south of Memphis, Tennessee. The top one was taken by a NASA satellite on August 8, 2012, and the bottom one by a different NASA satellite on August 14, 2011. See how there are huge patches of light tan along the river in the image from 2012? Those are newly exposed sand bars, the result of record low water levels.

This summer's record-setting temperatures (July was literally the hottest month on record) and dry weather conditions have created historic droughts. We can now see how those conditions have affected our waterways. On August 17 of this year, water levels in the Mississippi were 2.4 to 8.3 feet below their normal "river stage" levels.

This has economic effects, as the NASA Earth Observatory blog points out:

The reduced river flow in 2012 has translated into millions of dollars in extra shipping costs, as the loss of just one inch of draft means that a barge can carry 17 tons less than it otherwise would. The result is decreased shipping capacity.

The current conditions are being described as "uncharted territory." There are potential health effects as well. The low river levels are creating a "wedge" of saltwater that's advancing up the river from the Gulf of Mexico and threatening drinking water in the area.

Natural processes used to occasionally create a "dead zone" of oxygen-poor water grows in the waters of the Gulf of Mexico. It would happen when nutrients from upstream got washed out to sea, feeding phytoplankton in the area. As that phytoplankton population exploded, and then decomposed, bacteria would absorb the water's oxygen, making it deadly to animals, from crustaceans to fish.

But these days farming fertilizers provide a regular source of nutrients to the phytoplankton, and the dead zone is a regular thing. NASA's Earth Observatory explains:

Once infrequent, the Gulf of Mexico dead zone is now an annual event, triggered by phosphorus and nitrogen in fertilizers used on farms throughout the central United States and as far away as Saskatchewan, Canada. In the fall, strong winds from seasonal storms stir the water, mixing the oxygen-poor deep water with oxygen-rich surface water, bringing a reprieve until the next spring.

It stands to reason, then, that the record flood swell right now making its way down the Mississippi River is going to pull a lot more of that nitrogen-rich fertilizer runoff into the Gulf and make that dead zone even bigger than normal years. Jenny Marder reports for PBS that this summer's dead zone is already the size of New Jersey, and growing. Marder quotes a marine scientist who warns that this will be the "largest ever amount of hypoxia," the phenomenon that causes the dead zone. It's also going to make life even tougher for already-suffering fishermen in the region:

Flooding could cause further injury to fisheries in the northern Gulf of Mexico, already reeling from last year's oil spill, Rabalais said. Dead zones alter the habitat for crab, shrimp, fish and lobster, often forcing them to shallow areas. This includes catchable seafood, like shrimp and snapper, which are vital to the area's fisheries.

After the Deepwater Horizon and the oil plume that still to this day is beaching tar balls, the last thing Gulf fishermen need is another "unnatural disaster" to deal with.

Basically, any river always wants to take the shortest and steepest route possible to its outlet. The Mississippi is no different, and since long before humans were around, it has jumped its banks every 1,000 years or so and charted a new, more desirable course. The image above shows the contrast between the long history of change in the Mississippi, and the Army Corp's plans for peak flow rates during massive 1-in-500 year floods. (Peter ran a nice full-length version of that first map in his post about the flooding Mississippi's impact on fish.) Sometime in the 1970s, the Mississippi River would’ve jumped its course and dumped into the much more inviting Atchafalaya River basin.

The mighty Mississippi River keeps on rollin’ along its final 300 miles to the Gulf of Mexico south of New Orleans—but unwillingly. There is a better way to the Gulf—150 miles shorter, and more than twice as steep. This path lies down the Atchafalaya River, which connects to the Mississippi at a point 45 miles north-northwest of Baton Rouge, 300 river miles from the Gulf of Mexico Delta. Each year, the path down the Atchafalaya grows more inviting.

The only thing preventing the river from taking that path is the Old River Control Structure. If that is compromised or breached, the impact would be enormous. The Mississippi would probably have a permanent new route to the Gulf of Mexico, and Baton Rouge and New Orleans—and all the towns in between—would be “stranded on a salt water estuary, with no fresh water to supply their people and industry.”

I really can't recommend highly enough that you read Masters' post in full. America's Achilles' heel is about to face its greatest test.

This Great Mississippi Flood of 2011 is a stark reminder to Americans of how the Mississippi River is not—and hasn't been for many decades—a naturally free-flowing body of water. It is, rather, a highly-engineered system of public works. (For the best piece I've ever read about how we try to wrestle these natural bodies into submission, read John McPhee's classic essay Atchafalaya.) And that highly engineered system is being tested by what Jeff Masters of Weather Underground describes as the "river's highest flood crest in history."

Downstream from Memphis, flood waters pouring in from the Arkansas River, Yazoo River, and other tributaries are expected to swell the Mississippi high enough to beat the all-time record at Vicksburg, Mississippi by 1.3' on May 19, and smash the all-time record at Natchez, Mississippi by six feet on May 21, and by 3.2 feet at Red River Landing on May 22. Red River Landing is the site of the Old River Control Structure, the Army Corps' massive engineering structure that keeps the Mississippi River from carving a new path to the Gulf of Mexico...Its failure would be a serious blow to the U.S. economy, and the great Mississippi flood of 2011 will give the Old River Control Structure its most severe test ever.

In times like these, I can't help but think that we might have lots to learn from the Dutch, who have probably know the most about how to live with water. Four years ago, Dutch authorities came up with a water management plan called "Room for the River." Reversing generations of water control convention, the Dutch decided that rather than battle rivers with expensive dikes and levees and canals, they'd give rivers more room to flow freely. This video explains the program.

Each spring, flooding on the Mississippi River takes tons of soil and nutrients downstream, and farmers across the Midwest—where the bulk of food in the United States comes from—replace that lost fertility with synthetic nitrogen fertilizers. There's no quick replacement for all that topsoil.

Over the last 150 years, the native tall-grass prairies here have lost 8 to 10 inches of topsoil, more than 50 percent, and the region appears to be losing soil faster than anticipated, according to a new report from the Environmental Working Group.

In Adair County, Iowa, state highway officials installed these five pillars at a rest area off Highway 80. They're designed to visualize the incremental losses of topsoil over time, showing the diminished height of soil and native vegetation.

It's a small reminder, but one more of us should see.

We need to pay attention to the next Farm Bill, which will develop farm programs that could emphasize better soil conservation, rather than creating incentives to plant more. As The New York Times put it in an incisive op-ed, "Erosion is not nature or bad farmers at work. It is the legacy of bad agricultural policy."

Last week's storm system, in combination with heavy rains earlier this month and over past 24 hours, pushed the Ohio River at Cairo, Illinois to 60.6 feet at 1am CDT May 1. This is the highest flood in history, besting the 59.5' mark of 1937 [sic]. Additional heavy rains of 2 - 4 inches are expected over the next five days, and the river is not expected to crest until Wednesday, at a height of 61.5 feet. As the record flood waters from the Ohio River pour into the Mississippi and are joined by melt water from the this winter's record snow pack over the Upper Mississippi, all-time flood heights are likely to be exceeded at many points along a 400-mile stretch of the Mississippi below its confluence with the Ohio.

Over the next couple of weeks, this historic surge will move down the Mississippi. Officials are warning that many cities and towns along the river will see record high flood waters, potentially surpassing levels reached during the great 1927 flood, and far exceeding those reached in the 1993 Mississippi Flood that so many of us remember from our youth.

We will continue to monitor the situation, and we hope that the slow moving nature of this potential disaster gives vulnerable parties time to prepare as best they can.

No man can move mountains, but our President just might move the nation's largest river.

File under: whoa.

The Beltway-connected historian Douglas Brinkley dropped something of a bombshell talking to Anderson Cooper about the administration's response to the Deepwater Horizon catastrophe. Brinkley suggests that on top of the short-term fixes—actually stopping the gusher and cleaning up the oil—the administration is planning a massive "Gulf Recovery Act" that would involve actually redirecting the Mississippi River in order to restore coastal wetlands, and sending the bill to BP. Brinkley says this could run as high as $20 billion, since it basically involves pulling the river out of the concrete channels that it's been funneled through for years now and flooding it back out through all of the degraded coastal areas it once ran through, regenerating wetlands and forming new barrier islands that have eroded over the decades as the flow of sediment stopped.

That would all be a heck of a big deal. A massive public works project on the scale of the Tennessee Valley Authority (which, long before it was flooding Tennessee towns with coal ash, was actually providing incredible public service and employment to the poor region), the endeavor, Brinkley assures Cooper, is more than a personal pipedream. In fact, Brinkley has the ears of administration insiders. Even James Carville, who's been crushing the president lately for his weak response, is blown away by the prospect. Here's the video, courtesy of CrooksandLiars:

RINKLEY: There are three things…going on. One is close that well…capture as much oil as you can, keep the pressure on BP on the relief wells. Second is immediate cleanup. And I think more can be done by the Obama administration…But I think the big third piece is coming, when President Obama comes to Florida and Alabama and Mississippi, and that is holding BP responsible for the Natural Resource Damage Act, for the Oil Spill Response Act. And, by that, I mean BP is going to end up paying somewhere from $10 billion to $15 billion, maybe even $20 billion, because they’re going — one of the only ways to save the Louisiana wetlands is going to be — you know, the Mississippi River has been channelized for navigation.

Well, now the Mississippi River has to be redirected. It’s going to have to be flooded and sediment pumped into these marshlands to save it. I think the Obama administration…

(CROSSTALK)

COOPER: So, no, wait. No, wait. Doug, is this just a hope on your part?

BRINKLEY: No.

COOPER: Or — I mean, I know you have been talking to sources. Do you believe this is actually going to happen?

BRINKLEY: Yes. Yes. It’s one of the reasons why the president is not talking to Tony Hayward. And they are going to come out with a large Gulf recovery act, because the oil and gas industry has been dredging. We have disappearing barrier islands. For 40 years down there, it’s abused the wetlands.

This is a turning point. There is an appetite on Capitol Hill for Gulf recovery act. The Mississippi River is going to have to be redirected into the marshlands. And BP and Transocean and other, you know, operations, Cameron, other companies are going to have to pay up to $10 billion and $15 billion for breaking national acts.

In addition, for offshore drilling in the Gulf, Anderson, there will be a conservation excise tax that, yes, there will be offshore drilling, but Louisianians will start getting some of the revenue to stay in state.

[...]

Congress is going to go after BP, and they have now broken, as I said, National Resource Damage Act, Oil Spill Response Act. And in order to save the wetlands, which BP is responsible to, it’s going to be — the Army Corps of Engineers has directed — if you fly over, it’s like a bird’s foot. There are three channels.

We’re now going to have to redirect Mississippi River sediment and flood the marshlands to try to save them. That will occur after this — the well gets capped, the relief wells are built. But, in the next year or two, this will be, for President Obama administration, I think something of a Tennessee Valley Authority or a Saint Lawrence Seaway under Dwight Eisenhower, a major public works act.

It's hard to overstate how massive an undertaking this would be, and it would pretty much slam the door on any "Is Obama doing enough for the Gulf" criticism. Though there's been curious little reaction to Brinkley's statement, so I'm in very cautious "believe it when there's a White House press release" mode.

Now I've been talking to lots and lots of urban planners and environmentalists in the area lately for a piece about climate adaptation and resiliency for our upcoming New Orleans issue. Everyone, withouth exception, speaks of wetlands restoration with wistful resignation. They consider it some pie-in-the-sky scenario that will never, ever happen, as there's no local authority that has the strength or resolve to stand up to private interests and make it happen. It almost certainly would take the White House pull off what the local agencies couldn't possibly. Let's hope the White House will.